Poultry Houses and Ammonia: Instrument Measurement Comparisons

(clicking drumbeat)

- [Dan] In this video, we are going to make comparisons of ammonia gas measurements from three different instruments.

A portable personal gas monitor, paper test strips, and colorimetric pole tubes.

These instruments can be used to take quick spot measurements to check the ammonia gas concentration in animal barns.

The first comparison was made in a turkey pen.

The handheld gas monitor was used to measure the ammonia gas concentration in the pen first.

The monitor was held at bird breathing level for several minutes to allow the instrument to reach a steady reading.

The measured ammonia concentration was between 18 and 19 parts per million.

Next, a paper test strip was used.

A small strip of ammonia test paper was torn from the roll and moistened with water.

The test strip was then held at the bird breathing level, and exposed to the air for 15 seconds.

After 15 seconds of exposure, the color of the test strip was compared to the color scale to determine the measured ammonia gas concentration.

It is difficult to see in this video, but the test strip indicated the ammonia concentration was between 10 and 20 parts per million.

The third instrument used was a colorimetric pull tube.

Both ends of the tube were carefully broken off, and the tube was inserted into the sampling pump with the arrow facing the pump.

The open end of the tube was held in the bird breathing zone, and the pump was operated by compressing the bellows and releasing them, allowing a precise volume of air to be pulled into the tube.

As you can see, the pull tube indicates the ammonia concentration was less than 10 parts per million, which was different from the other instruments used.

We will discuss this difference later in the video.

The instruments were also compared in a controlled environmental chamber with a known ammonia gas concentration of 40 parts per million.

The handheld gas monitor was used first.

The monitor was placed near the birds, and measured a gas concentration of 40 parts per million.

A paper test trip was used next.

After 15 seconds of exposure near the birds, the measured gas concentration was between 20 and 50 parts per million.

A pull tube was used last.

An air sample was taken near the birds, and the measured concentration was approximately 40 parts per million.

Let's look at the instrument measurements side-by-side, discuss the differences, and talk about how these can be used on your farm.

The images along the top show the measurements taken in the turkey pen, and the bottom images show the measurements from the environmental chamber.

The measurements from the handheld gas monitor and paper test strip agreed in the turkey pen, but the pull tube measurement was too low, and all measurements taken in the environmental chamber were in agreement.

So which measurement do you trust, and how is each one useful?

Each instrument has an error range associated with its measurements.

A handheld monitor and pull tube might both be accurate within plus or minus 15%, but the information obtained is a little different.

The handheld gas monitor gives you a number that you can write down in your records, but to trust the measurements, the monitor must be calibrated and bump tested regularly.

Paper test strips give you a range of values that bracket the actual gas concentration in the barn.

For example, the measurement taken in the environmental chamber was 40 parts per million using the handheld gas monitor, but the test strip could only tell us that the concentration was between 20 and 50 parts per million.

Even though it does not give you an exact number, this would be very useful for quick spot checks to see if the ammonia level in your barn is below an acceptable level.

Pull tubes include a linear scale that is easier to interpret than the color range of paper test strips, and you can make an estimate of the actual gas level for record-keeping, but the measurement is still not as precise as the number obtained using a handheld gas monitor.

As we showed earlier while measuring gas levels in the turkey pen, user error may result in an inaccurate reading, so multiple tubes might be needed if you want to verify a suspect measurement, ultimately the decision about which instrument to use on your farm depends on your individual needs.

For more information about each type of instrument, check out the other videos and fact sheets available on the Penn State Extension website.